The present invention comprises certain improvements in a tire press of the type manufactured and sold by NRM Corporation of Columbiana, Ohio, U.S.A., under the trademark AUTOLOK. Such presses are generally illustrated for example in U.S. Pat. Nos. 4,338,069 and 4,332,536, and are twin cavity presses wherein the top cavities of the press are supported from a single center circular column for opening and closing. The top cavities are locked to the bottom cavities by rotating bayonet lock rings. The upper cavity or mold sections may be supported for such movement from a V-shape beam. However, the presence of the beam comprises an obstruction if fairly complex top center assemblies or mold height adjustment mechanisms are employed. Such center assemblies may be rather complex and project above the top cavity and operate, for example, sectional molds, the top mold bead ring, and top loading chucks. Both clearance and access to such assemblies is required for maintenance and replacement purposes. Accordingly if the top mold cavities can be supported properly laterally of the upper mold cavities from the center column a more functional and lower cost press can be provided.
Also, in the precision curing of tires mold alignment is a matter of concern, and is sometimes difficult to achieve, particularly with complex frame structures. The single center column of the present invention is particularly suited for obtaining precise mold alignment. The twin cavity upper structure of the press may swing on the vertical axis of the column, and if properly guided on the exterior or remote from the center column at only a single location, the proper alignment of both cavities may be achieved. If the single alignment guide is about twice the distance from the axis of the column as the mold axis, any misalignment at both mold axes will be only about half such misalignment. Moreover, with the approximate two-to-one factor adjustments are easier to make. It has been found that such alignment guiding may conveniently be from one of the loader columns in front of the press.
Precision tire curing also requires precision loading of the press. This requires that the tire be picked up properly and held properly for subsequent transfer to the bead rings of the molds. Because tire sizes change a loader requires substantial versatility and in fairly limited space. The ideal place to pick up a tire for loading is at the belted tread area leaving the bead area free. This however requires a loader chuck of substantial diameter. One way of gripping such tires is through the use of an inflatable bladder as shown in U.S. Pat. No. 4,447,385. However, such bladder type chucks don't have the precision of adjustability or versatility of reach of mechanical chucks. Accordingly a mechanical chuck which will fit in a large diameter circular yet radially narrow space and still have precision adjustability and substantial reach is desirable.
Also, with fairly massive tires the loader should be able to raise the tire from a precise pick-up position, move or swing it to a position aligned with the mold axes, and then possibly further raise or lower the tire, all without excessive shock to the tire, which could cause damage or misalignment.
The top loading of uncured tires has been developed as a superior manner of introducing uncured tires into a tire press. The preferred process brings the uncured tire top bead initially adjacent the extended top mold bead ring, then the bottom mold bead ring. At this point the tire may be air inflated to center and snap the beads of the uncured tire onto the mold bead rings. As an illustration of tire presses utilizing a top or bead ring loading process, reference may be had to U.S. Pat. Nos. 4,447,385; 4,444,715 and 4,608,219. A top center assembly for such process requires a chuck which is simple and compact and yet quite sturdy. The chuck must also be readily adjustable to control the extent of opening.
It is also desirable that the chuck be simple to operate and yet operate properly and in conjunction with other actuators in the fairly complex top center assembly of each mold cavity. The chuck should also be able to operate with any type center or shaping bladder mechanism. It should also not interfere with the air inflation of the uncured tire for centering and seating of the beads. The inlet for such air inflation should be axially aligned with the beads and yet not sufficiently close to the tire or beads in any way to cause the tire to move off center.